address inconsistent filenames in converter/converters #185

I think the standard should be koki_<resource>_to_kube.go and kube_<resource>_to_koki.go.

• It's redundant to have <resource> in the filename twice.
• Each converter file handles all versions of the resource, so v1 etc isn't needed.
• The filename needs to specify which direction it implements. koki -> kube vs kube -> koki